brooklynwx99

Classic pattern progression yet again on the 12z GEFS. SWFEs and overrunning events to slow-moving coastal systems. Wow.

The period from 2/20 through early March could be quite historic, in my opinion. This will occur in two distinct "phases." 1) There will be a large thermal gradient with the NE in the cross hairs as a 500mb SE ridge takes shape. Although these always appear unfavorable looking at misleading anomaly maps, this feature is vital if you want an active pattern. In fact, there is a strong cold air feed at 2m due to the -NAO taking shape, which forces lower than average heights and HP in the 50/50 region and SE Canada. This pattern might look unfavorable for the E US at a quick glance, however, look at the 2m temperature anomalies valid for the same time frame: There isn't a warm spell in sight. This shows me that there is HP entrenched in SE Canada, which establishes a strong cold press into the NE US. Coupled with the SE ridge aloft, there could be numerous cold SWFEs and overrunning events. Coastals aren't too likely with that upper air setup, but those two storm types can produce prolific snowfall amounts on the right side of the thermal gradient (which I believe the NE US will be on). Also, notice the classic NAO/EPO/AO ridge bridge becoming established. This will set the stage for the second "phase." 2) As the polar blocking fully develops and ridging builds in the EPO and PNA domains, the mean trough will begin to migrate eastward. This will open up chances for major coastal systems to impact the E US. Here, the NAO blocking begins to retrograde into the Davis Strait, and the longwave trough moves into the C US as the western heights begin to rise with a strong STJ into S California. Everything is there: high heights throughout the polar regions, a broad trough over the C US extending into the E US, and a defined 50/50 signal. This is a little harder to see, but the TPV is elongated throughout SE Canada, which opens up a wide variety of phasing scenarios. This is an amazing look, and "thread the needle" won't be uttered often if this pattern comes to fruition. Overall, I believe that this is the best pattern that we have seen all winter, and it could prove to have historic results if it indeed comes to fruition.

Hey, wanna know what this looks like? Sorry I haven't been posting much, but every time I see a 500mb map like this it catches my attention because of this composite. This very type of pattern produced a blockbuster March last winter, so it's definitely striking to see modeled, even at long range.

The 12z GEFS is completely off-base in its depiction of above normal heights in the E CONUS in the extended 10-15 day period. In fact, the smoothing out of features in long range ensemble modeling is causing some discrepancies wrt accurate height forecasting. One would look at this and say "this is a warm look for the E US, winter cancel" if they put in zero effort in trying to decode what the model is actually showing. However, there are a couple features that make this pattern rather exciting for us: 1) There is an absolutely massive -NAO/AO signal which actually builds in strength as you move further out in time, which is quite rare. These types of blocks have the ability to dictate the pattern on their own, as we saw last March, where a -PNA was overcome by an intense retrograding cutoff ridge into the Davis Strait and C Canada. We are finally beginning to see the effects of the SSW consistently show up on ensemble modeling. 2) There is a very strong split flow signal, which will provide multiple opportunities for phasing scenarios down the line. If you look at the actual source region for the E CONUS, you will be able to see why the GEFS is lost with its "ridging" in that part of the country. First off, the NS is coming out of Alaska, and a cutoff ULH near Siberia helps to pull in fresh polar air. The numerous HPs from the ULH into Canada and the N CONUS are good evidence of this. Sure, there is some Pacific influence, but if you look near WA and OR, the 250mb winds are very weak due to the split flow, so this is nothing like earlier in the winter where there was a 100+ kt jet right off of the WC. The SS looks to have a "Pineapple Express" look, as it moves right through SW CA; the STJ would certainly be open for business. The culmination of these features leads to a broad jet streak over the EC, which aids in storm development. Overall, the SSW and tropical forcing which have been discussed ad nauseum over the last couple weeks are beginning to manifest itself positively; the GEFS is great proof of that, even if it looks "unfavorable" from a quick glance.

This isn't aimed towards you specifically (you're new to tracking), but one of my biggest pet peeves when tracking winter storms is the whole "this can go wrong, so this threat isn't feasible" mentality. If you look long enough, you will always find something wrong with a setup. SECS and up are nearly always thread the needle events, which is why they're so significant in the first place. With this threat, there's a highly anomalous PNA ridge, an elongated TPV, and transient ridging in the NAO domain. That's all I need to see for a possible threat a week out.

Deep, deep winter. 11F.

Me reading the last 2 pages of this thread

Again, just look at this setup. Massive PNA ridge extending poleward into the EPO domain and into Siberia with a perturbed TPV via NAO blocking. There's a ton of potential here, and it would be intellectually dishonest to deny that. This ensemble mean at 150+ hours is showing a phase between the TPV lobe and the SS energy. If that isn't good enough for you at this lead time, then I don't know what to say.

Some of you really need to take a break. I can't possibly understand how someone can trash this setup. It's unwarranted and is solely based on feelings rather than actual meteorological evidence. It's becoming hard to read, quite frankly.

Beautiful here in State College. SN, about 5” OTG. Expecting 10-14”.

Throughout the next week and beyond, the entire Northern Hemispheric pattern will shift to one that is much more favorable for winter storms in the NE CONUS. The Pacific jet will retract, allowing for strong positive anomalies to build in the PNA and EPO regions, and NAO/AO blocking will also increase dramatically due to the intense stratospheric activity that we've seen over the last few weeks. The TPV will elongate due to the NAO blocking, which will allow for a large temperature gradient to form in the N US and SE Canada. This type of setup is so favorable because of how many types of storms can form. Overrunning is a great option because of the established thermal gradient, which will produce strong lift even without a strong LP center, and lobes of energy rotating down from the TPV can phase in with SS energy to form Miller A/Bs. Overall, I am very excited for the upcoming time period, and I expect multiple threats between now and the first week of February. Also, just because NYC or your backyard doesn't get snow, that does not mean that the pattern hasn't changed. This is a complete hemispheric shift from what we saw for most of December, and I expect the new pattern to pay dividends for the E US.

I swear you guys are incredible sometimes

This really reminds me of the November storm. The cold press is strong, and these trends could continue until game time. Cold air is relatively dense, and it takes a lot of force to expel it. NYC is almost in the game for significant winter weather. Let’s see how other models trend.

In the past three runs, the GFS has made a consistent shift towards more negative northern stream interaction. This is the same kind of poor angular momentum that has suppressed our two other large storm chances, and it has made a rather significant reduction of heights over the NE since 06z. These seemingly minor shifts can have drastic effects on those near the coast, as a few more compressions of the height field can lead to a more favorable outcome for those in the NYC metro. It's certainly something to keep an eye on for those on the cusp.